Supported catalysts have been used for the growth of arrays of carbon nanotubes (CNTs). The supported catalysts typically include metal particles of Fe, Ni, Co, and Mo on a solid support such as a solid support of silicon. When the supported metal particles are exposed to a carbon source at an elevated temperature, the metal particles catalyze a decomposition of the carbon source that results in an array of aligned CNTs on the support in a direction perpendicular to the support surface (see, for example: Hata et al., Science vol. 306, p. 1362, 2004).